A typical high power, radio frequency (RF) semiconductor device may include one or more input leads, one or more output leads, one or more transistors, bondwires coupling the input lead(s) to the transistor(s), and bondwires coupling the transistor(s) to the output lead(s). The bondwires have significant inductances at high frequencies, and such inductances may be factored into the design of input and output impedance matching circuits for a device. In some cases, input and output impedance matching circuits may be contained within the same package that contains the device's transistor(s). More specifically, an in-package, input impedance matching circuit may be coupled between a device's input lead and a control terminal (e.g., the gate) of a transistor, and an in-package, output impedance matching circuit may be coupled between a current conducting terminal (e.g., the drain) of a transistor and a device's output lead. Each of the input and output impedance matching circuits may include one or more capacitive and resistive elements, along with the inductances inherent in the sets of bondwires interconnecting those elements with the device's transistor(s) and with the input and output leads.
Such packaged RF semiconductor devices are readily available, which have very good performance when used in narrow-band applications. However, designing suitable packaged RF semiconductor devices for wideband, multi-band, and/or multi-mode operation is challenging for several reasons. For example, in a packaged RF semiconductor device, the lead level output impedance is limited by the number of matching sections. Therefore, to achieve an acceptable lead level output impedance for a wideband, multi-band, and/or multi-mode application, it may be desirable to incorporate multiple, in-package matching sections. However, the inclusion of multiple matching sections in a device increases the number of impedance matching elements in the impedance matching circuits, and thus increases the size of the device. In addition, the various sets of bondwires that would be implemented to interconnect the impedance matching elements for multi-stage matching may create unacceptable inductive coupling between the matching sections, which may limit the effectiveness of the impedance transformation. In addition, to facilitate good performance for wideband, multi-band, and/or multi-mode implementations, relatively large discrete capacitors in the impedance matching circuits may be warranted. Accordingly, in order to accommodate the relatively large capacitors, package sizes for such implementations would need to be further increased. Increasing semiconductor device package size is incompatible with the industry trend to reduce device sizes and costs.